#include <51func.h>
int main(int argc, char *argv[])
{
    printf("Hello world 1\n");
    int fd_pipe = open(argv[1],O_WRONLY);
    int fd_backup = 10;
    dup2(STDOUT_FILENO,fd_backup);
    dup2(fd_pipe, STDOUT_FILENO);
    printf("Hello world 2\n");
    dup2(fd_backup,STDOUT_FILENO);
    printf("Hello world 3\n");
    return 0;
}

